Controller



Oct. 10, 1939. K. J. UNwlN 2,175,932

I CONTROLLER Filed April l, 1938 Iii.

l um

Hi Attorney.

Patented Oct. 10, 1939 PATE-NT ol-FlE CONTROLLER Kenneth J. Unwin, Schenectady, N. Y., asaignor to General Electric Company, a corporation of New York Application April 1, 1938, Serial No. 199,432

9 Claims.

My invention relates to electric switches or controllers, more particularly to cam-operated limit switches, and has for an object the provision of a simple and inexpensive device of this character which will be rugged and reliable and which will afford. accurate timing in the performance of its control function.

In controlling the automatic operations of machines such as shapers, planers, milling machines, and lathes, it is desirable that accurate control timing should be provided to avoid tool breakage and the spoilage of expensive work. It is also desirable that the switch operate with a positive snap action to aii'ord a definite timing from the beginningv to the end of the actuation period and to prevent arcing at the switch contacts. [Further, it is desirable to provide means for moving the actuating cam of the controller out of the path of the tool or machine member which actuates it to allow free over-travel of the member before reversing.

In carrying out my invention in one form, I provide a controller having a rotatable operating shaft carrying an actuating cam at one end and a bifurcated actuating plate at the other end thereof. A switching shaft is provided which carries a switching member and an armature secured thereon having two arms which cooperate pivotally mounted spring guide is an over-centerhelical spring adapted to carry theactuating cam out of the path of the actuating member of the machine to be controlled, -after the switch has been actuated.

The magnetic restraint between either of the amature arms and the permanent magnet is broken by the push of a bumping ear carried by the bifurcated actuating plate. A torsion spring encircling ,the operating shaftl is provided for damping the mechanical blow of the bumping ear on the armature. sists the oncoming bumping ear in such a manner that the armature must be positively pushed away from the holding magnet instead of being kicked or knocked away from this position. As

soon as the mangetic restrain is overcome, the wound-up torsion spring causes the armature to snap to its operated position slightly ahead .of the bumping ear on the actuating plate, which together with the actuating cam isbeing snapped ahead of the machine member; the machine member is thus enabled to move on ahead free of .right by welding or other suitable means.

The torsion spring first' re-l 1 the actuating` cam and upon its return movement to move freely into an engagement with an appropriate reverse projection on the cam.

For a more complete understanding of my invention, reference should be had to the accompanying drawing in winch Fig. lis an elevational view of a controller embodying my invention with the cover plate removed; Fig. 2 is a sectional view taken along line 2--2 of Fig. 1 showing the switch operated to a first position; Fig. 3 isa plan view with the top of the casing removed along the line 3--3 of Fig. 1 to reveal the details of the inner construction; Fig. 4 is a sectional view taken along the line 2-2 of Fig. 1 showing the switch operated to a second position; Fig. 5 is a sectional view taken along the line 5-5 of Fig. l; Fig. 6 is a perspective view of certain'details of various elements in the switching mechanism; and Fig. 'I is a schematic view showing the operation of the cam and the actuating member.

Referring now to the drawing, I have shown my invention in one form as applied to a cam-actuated machine-tool limit switch. The mechanism is shown.. enclosed in a suitable casing l comprising a top wall Il, a bottom wall or base I2, a front wall Il, a rear wall I4, and two cover plates l forming the side walls thereof. Mounted within the casing .It on the -base I2 andv secured thereto by screws II is a supporting member II having two upright projections lilv and I9 containing holes and 2| adapted to receive bearing members v22 and 2J. From the front surface of the front upright projection I8 are secured two soft iron pole plates 24 and 25 which are spacedapart to receive a permanent magnet 26 therebetween. The soft-iron pole pieces 24 and 25 may extend horizontally in substantially parallel relation to each other at the upper end of d the upright Il and may be secured to the up- 'I'he permanent magnet 26 may be cube-shaped having its upper and lower faces secured in close magnetic relation tothe inner faces of the soft iron pieces by suitable means. The permanent magnet 2t may be of some good magnetic ma- .terial such as that described in United States Letters Patent 1,947,274 to W. F. Ruder which issued onebruary 13, 1934, and is assigned to the Present assignee.

Journaled through'the bearing members 22 and 23 is a switching shaft 2'I. The switching shaft 21 has fixed at the forward end thereof an operating member comprising an armature 28 having two arms 29 and Il which Vareangularly displaced from each other and which cooperate with the permanent magnet 26 positioned therebetween to be magnetically restrained in either of the two positions in contact with the beveled surfaces 0n either side of the pole plate 24. Secured on the switching shaft 21 by the screws 33 is a movable switching member 3| of insulating material having ali/support 32 and a pair of .bridging contacts 34 and 35` (see Fig. 5) supported at the top of the supporting member 32 by`a separating arm 36 encircled at each of its extending ends by the helical compression springs 31 and 38. The contact strips 34 and 35 of suitable conducting material having a pair of Contact tips 39 and 40 at eachend thereof are carried at the ends of the separating arm and maintained in position by the end nuts 4| and the bias of the compression springs 31 and 38. A pair of spaced apart insulating-supports 42 and 43 secured on the upper face `of the member |1 by the screws I6 extend upwardly from the base of the casing |0, one on each side of the shaft 21. A pair of terminals and fixed contacts 44 and 45 are carried by each of the supports 42 and 43 to cooperate with the bridging contacts 34 and 35 for completing an electrical circuit (not shown) One set of fixed contacts is in engagement with its mating set of movable contacts in each of the two positions of the armature arms 29 and 30, the other sets of contacts being then disengaged.

.Iournaled in the front wall I3 of the casing I0 andextending therethrough is an operating shaft 46 carrying at the outer end thereof an actuating cam 41 which is fastened to the shaft 46 and adjustable by means of a screw 48. The operating shaft 46 may be in substantially parallel axial alignment with the switching shaft 21 and positioned slightly abovev the axis of the switching shaft 21 to provide for a greater angular movement of the cam 41 than the angular movement of the armature 28. Secured at the inner end of the operating shaft 46, is a bifurcated member 49 having ,a pair of. angularly displaced bumping ears 50 and 5| which cooperate with a bumping projection 52 extending from the armature 28 for dislodging the armature 28 from either ofI its positions for movement to the other of its positions.

Riveted to the inner surface of the front wall I3 of the casing ||J is an angular guide support 53 having a hole 54 therein. Projecting through the hole 54 at its upper end and extending downwardly, journaledl on a pin 55 fastened to the actuating plate 49, is a spring guide 56 carrying encircled thereon an over-center helical spring 51. The over-center spring 51 is so arranged that in its dead-center position both of the bumping ears 50 and 5| are out of contact with the cooperating projection 52 on the armature 28 no matter which of the two positions the armature 28`has assumed.

Encircling the operating shaft 46 adjacent to the actuating plate 49 is a torsion spring 58 having two free ends which are in one-way engagement with the projection 52 on the armature 28 and a detent 49 on the actuating plate 49, respectively, upon rotation of the actuatingplate 49`in either direction. The controller may be actuated by an appropriate member 59 (indicated diagrammaticallylon the machine or tool to be controlled which cooperates, respectively, with the curved operating arms 60 and 6| of the cam 41 in its forward and reverse movement to operate the switching mechanism to the two positions (shown in Fig. 7)

As shown in Fig. 1 and Fig. 2,Y the controllerA is in its first position with the arm 30 of the armature 28 being magnetically restrained in contact with the beveled edge of the soft iron pole plate 24 of the permanent magnet 26. The switching shaft has been rotated clockwise to the first position, as viewed in Fig. 5, so that the bridging contact 35 completes an electrical circuit with the stationary contacts 45. This circuit may include a reversible electric motor to cause the machine member 59 to be moved into contact with the curved arm 60 of the cam 41 for bringing about a reversal of the motor after a predetermined movement of the machine member 59.

As the cam 41-and the operating shaft 46 is caused to rotate from its rst position in a clockwise direction, as viewed in Fig. 2, the rotation is initially opposed by the over-center spring 51 acting through the spring guide 56 and the pin 55 on the actuating plate 49 which is secured to the shaft 46. The initial opposition of the over-center spring 51 against the rotation of the shaft 46 prevents a premature operation of the controller which might occur by a high speed blow of the machine member 59- on the cam 41. As the clockwise rotation of the shaft 46 proceeds, the over-center spring 51 reaches a deadcenter position before the bumping ear 50 on the actuating plate 49 engages the projection 52 of the armature 28. At the same time the detent 49 on the actuating plate 49 engages one free end of the torsion spring 58 whose other free end is now in engagement with the projection 52 on the armature 28. The torsion spring 58 then begins to oppose the rotation of the actuating plate 49 and the force of the over-.center spring 51 which tends to complement the rotational forces in the direction of rotation after passing its dead-center position.

The torsion spring 58 may be made of sutilcient strength to exactly oppose the force of the over-center spring 51 on the actuating plate 49 to dampen the mechanical blow of the bumping ear 50 on the armature projection 52. For sensitive and precise operation of the controller, this damping effect of the torsion spring 58 on the bumping ears is important to avoid an undesirable vcondition of operation. Damping of the mechanical blow of. the bumping ears enables the armature arms to be pushed away from the restraining magnet 26 instead of being prematurely knocked or kicked out of the restrained position.

After the armature arm 30 is pushed away from the holding magnet 26, it is snapped to the operated position by the energy stored in the torsion spring 58. Upon a slight additional movement of the actuating plate 49, the overcenter spring 51 is moved far enough over center to apply a force in the direction of rotation greater than the opposing force of the torsion spring 58, to cause the arm 60 on the cam 41 to snap out of the path of the machine member 59. Thus, the machine member 59 can move on ahead free of. the cam 41 and upon return movement move over the arm 60 freely into engagement vwith the arm 6| of the cam 41 for operation of the controller to the opposite position.

essy

The controller in its second position is best illustrated in Fig. 4. The arm 29 of the armature 28vi's held by the permanent magnet 26 in contact with the beveled edge of the pole plate 24. The bridging contact 34 is in engagement with the fixed contacts 44 to complete a second electrical circuit (not shown). The machine member 59 having reversed its direction of mo- 'Il tion after the controller was moved to the sec- 0nd position, returns and engages the curved arm 6I of the cam I1 to cause a snap return of the controller to its rst position, by causing the bumping ear 5I to engage the projection 52 on the amature 28 to break the magnetic restraint on the amature. In this sequence, the torsion spring again first dampens the mechanical blow of the bumping ear 5I and then causes the armature 28 to snap to the operated position after the restraint of the holding magnet 26 is overcome. The force of the over-center spring 51 is then strong enough to snap the arm 6i of.- the cam 41 out of the path of the machine member 59 for free over-travel of this member preparatory to reversing. The operation of the various elements of the controller is analogous on either` side in the movement of the controller, and the reversing of the controller may continue indetlL nitely in this manner.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

11. A controller for'a machine adapted to be actuated by a member of the machine to be controlled comprising a rotatable switching shaft, switching means secured to said shaft at one point for operation thereby, means including a permanent magnet and an armature which is secured to said shaft at another point for restraining said switching means in either of two positions, means including a rotatable operating shaft and an actuating element associated therewith for breaking the restraint of said permanent magnet, a member secured to said operating shaft for receiving the'actuating force of said machine member, and means including an over-center spring for snapping said member out of the path 0f said machine member afterv a pre-determined movement thereof.

2.. A controller for a machine adapted to be actuated by a member of the machine to be controlled comprising a rotatablev switching shaft, switching means operable by said shaft, means for restraining said switching means in either of two positions, means including a rotatable operating shaft and an actuating element associated therewith for breaking the restraint of said restraining means, means for damping the mechanical blow of said actuating element in breaking said restraint and for snapping said switching means from either of said positions to the other of said positions when said restraint is broken, a member secured to said operating shaft for receiving the actuating force of said machine member, and means for snapping said member out of the path of said machine member after a pre-determined movement thereof.

3. A controller for a machine adapted to be actuated by a member of the machine to be controlled comprising a rotatable switching shaft,

switching means operable by said shaft, means including a permanent magnet for restraining said switching means in either of two positions,

means including a rotatable operating shaft and ing said magnetic restraint and for snapping said switching means from either of said positions to the other of said positions when Isaid magnetic restraint is broken, a cam secured to said operating shaft for receiving the actuating force of said machine member, and means including an over-center spring for snapping said cam out of the path of said machine member after a predetermined movement thereof.

4. A controller adapted to be Aactuated by a member of the machine to be controlled comprising a casing containing therein spaced apart pairs of fixed contacts, a rotatable shaft, a switch member secured to said shaft for movement relative to said fixed contacts, a permanent magnet, an operating member mounted on said shaft comprising an armature having two arms adapted to be magnetically restrained in each of two positions, a rotatable shaft in parallel axial alignment with said first-mentioned shaft journaled in said casing and extending therethrough, a cam on the outer end of said second shaft for actuating said shaft, an actuating plate mounted on said second shaft within said casing having a pair of angularly spaced apart bumping ears adapted to strike said operating member for overcoming the magnetic restraint when said operating member is in either of said positions, means including a torsion spring for damping the mechanical blow of said bumping ears on said operating member and for snapping said armature from either of said positions to the other of spring for snapping said cam out of the path of said machine member after a. predetermined movement thereof. v

5. A controller adapted to be actuated by a member of the machine to be controlled comprising a rotatable switching shaft, an operating member secured to said shaft comprising an armature having two arms angularly displaced from each other, a permanent magnet positioned between said arms adapted to magnetically restrain said operating member in either of two positions, a plurality of spaced apart pairs of fixed contacts, a switching member secured to said shaft movable relative to said fixed contacts, a rotatable operating shaft in parallel axial alignment with said switching shaft having an actuating plate secured thereto adjacent said armature, said actuating plate having a pair of angulariy displaced bumping ears adapted to operate said operating member from either of said two positions to the other of said positions, a cam secured to said operating shaft adapted to receive the actuating force of said machine member, and means including an over-center spring and a spring guide 'pivotally secured to said actuating plate for rotating said cam out of the path of said machine member after a pre-determined movement thereof.

6. A controller-adapted to be actuated by a member of the machine to be controlled comprising a casing containing therein spaced apart pairs of fixed contacts, a rotatable shaft, a switch member secured to said shaft for movement relative to said fixed contacts, a permanent magnet, an operating 'member mounted on said shaft comprising an armature havingtwo arms adapted to be magnetically restrained in. each of two positions, a rotatable shaft in parallel axial alignment to said first-mentioned shaft journaled in said casing and extending therethrough, a cam on the outer end of said second'shaft ,for actuating said shaft, an actuating plate' mounted on said second shaft adjacent said operating member having a pair of angularly spaced apart bumping ears adapted to strike .said operating member for overcoming the magnetic restraint when said operating member is in either of said positions, a torsion spring having two free ends encircling said second shaft adjacent said actuating plate, means including a projection on said operating member and a detent on said actuating plate for providing respectively opposite oneway engagement with said spring ends in either direction of rotation of said actuating plate, said spring being adapted for damping the mechanical blow of said bumping ears on said operating member and for snapping said armature from either of said positions to the other of said positions when said magnetic restraint is overcome, and means including a spring for moving said cam out of the path of said machine member after a pre-determined movement thereof.

'7. A controller adapted to be actuated by a member of the machine to be controlled comprising a casing containing therein spaced apart pairs of fixed contacts, a rotatable shaft, a switch member secured to said shaft for movement relative to said fixed contacts, a permanent magnet, an operating member mounted on said shaft comprising an armature having 'two arms adapted to be magnetically restrained in leach of two positions, a rotatable shaft in parallel axial alignment to said first-mentioned shaft journaled in said casing and extending therethrough, a cam on the outer end of said second shaft for actuating said shaft, an actuating plate mounted on said second shaft adjacent said operating member having a pair of angularly spaced apart bumping ears adapted to strike said operating member for overcoming the magneticrestraint when said operating member is in either-of said positions, a torsion spring having two free ends encircling said second shaft adjacent said actuating plate, means including a projection on said operating member and a detent on said actuating plate for providing respectively opposite one-way engagement with said spring ends in either direction of rotation of said actuating plate, said spring being adapted for damping the mechanical blow of said bumping ears on said operating member and for snapping said armature from either of said positions to the other of said positions when said magnetic restraint is overcome, and means including an over-center spring and a spring guide pivotally secured to said actuating plate for rotating said cam out of the path of said machine member after a pre-determined movement thereof.

8. A controller for a machine adapted to be actuated by a member of the machine to be controlled comprising a rotatable switching shaft, switching means operableby said shaft, means for restraining said switching means in either of two positions, means including a rotatable operating shaft and an actuating element associated therewith for breaking the restraint of said restraining means, means for damping the mechanical blow of said actuating element in breaking said restraint and for snapping said switching means from either of said positions to the other of said positions when said restraint is broken, and a member in operating relation with said operating shaft for receiving the actuating force of said machine member.

9. A controller for a machine adapted actuated by a member of the machine to be cor trolled comprising a rotatable switching shai switching means operable by said shaft, mea' including a permanent magnet and a bifurcate armature for restraining said switching means in either of two positions, said armature being secured to said switching shaft, means including a rotatable operating shaft and an actuating element associated therewith to transmit a mechanical blow to said armature for breaking the restraint of said permanent magnet thereon, and means including a helical spring encircling said operating shaft for snapping said switching means from either of said positions to the other of said positions when said restraint is broken.

KENNETH J. UNWIN.

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